578
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
The
k
v
values measured by oedometer test and
k
h
values
deduced from CPTu test are compared with each other in Figure
6. The values of coefficient of permeability from back-analysis
and falling-head permeability tests are also presented in Figure
6. The comparison shows that the
k
h
values measured by
oedometer are lower than those obtained from CPTu test within
1-2 order of magnitude. The coefficient of permeability of
Taihu lacustrine clay is in the order of 10
-5
-10
-7
cm/s. The
k
h
value measured by falling-head permeability tests agrees well
with that determined by CPTu tests.
6 REFERENCES
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20
15
10
5
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1E-8
1E-7
1E-6
1E-5
k h (cm/s)
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Figure 6. Comparison of k
h
profiles measured by different methods
4 CONCLUSIONS
The comparison of various cone sizes and configurations
between China CPT and international standard CPTu device at
28 field testing sites is presented. The relationships of derived
key parameters are developed between China CPT and
international CPTu. From the perspective of engineering
practice, it is concluded that
q
t
= 1.03
q
c
，
f
s-CPTU
= 1.05
f
s-CPT
.
The empirical equation can be used as useful engineering tool to
guide use of 10 cm
2
international CPTu in China. The field
CPTu tests were carried out in Jiangsu sites to evaluate the
stress history. Consequently, we obtained the value of
N
σt
factor, which is equal to 2.7 according to the correlation
relationship for Lianyungang lightly overconsolidated clay. The
results show that ratio of
M
derived from Kulhawy and Mayne
1990’s method to that determined from laboratory oedometric
tests,
M
-CPTU
/
M
-lab
, practically equals to 2.21 for high plasticity
clays. A quick estimation of the magnitude of coefficient of
consolidation c
h
is proposed by pore pressure dissipation (type
u
2
) tests from the CPTu database. Comparisons of the results
obtained by different methods indicate that the values of
horizontal coefficient of consolidation determined by CPTu are
typically 4 to 6 times those of laboratory tests. The coefficient
of permeability values measured by laboratory tests are less
than by almost 1-2 orders of magnitude with that determined by
CPTu tests in Jiangsu soft clays.
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5 ACKNOWLEDGEMENTS
The work in this paper was funded by the National Natural Scie
nce Foundation (Grant No. 41202203) of China,“Twelfth five-y
ear” National Science and Technology Support Plan (Project No
. 2012BAJ01 B02) and the Key Project of Natural Science Foun
dation (Grant No. BK2010060) of Jiangsu Province of China.
